According to clinical studies a staggering 37.6% of all self-administered eye drops miss the eye. One way to improve delivery of eye drops is by providing a visual feedback means so that a person dispensing drops can position an eye drop dispenser at an optimal distance and orientation above the eye. To accomplish visual feedback, the eyedropper needs to incorporate features used in other visual range and orientation devices. One such device is a common range finder used by golfers to gauge their distance from the ball to the hole. In golf range finders, the golfer stands near their ball and looks through a lens directly at the flag on its pole. The flags are uniform at a fixed height above the ground. The closer a golfer is to the flag, the larger it appears in the range finder. The range finder has calibrated hash marks within that correspond to a given distance. The golfer by aligning the appropriate hash mark with the image of the flagpole gets distance feedback. It will be appreciated that if the flagpole were replaced by a circular target, feedback of both distance and horizontal/vertical orientation can be visualized. With some optics engineering this mechanism can be used to gauge distance and orientation between a dispensing tip and the eye.
For years, the primary method of medically treating disorders of the eye has been via topical administration of various medications and other chemical compounds useful in combating a host of ophthalmic ailments. In fact, studies show that when measuring concentrations of these compounds at the desired target site (whether it be in the tear film, intracorneal, or intraocular), topical delivery equals or exceeds those concentrations obtained by systemic routes (oral or intravenous), and has far fewer systemic untoward signs and symptoms (side effects). Thus, it is no wonder that most remedies and medications are delivered via the topical route. Historically, this has been achieved via ointments, suspensions, solutions, contact lenses, collagen shields, and palpebral inserts. Far and away, the most common mode of delivery has been via topical suspensions and solutions. Typically, dispensers have fairly standard sizes and shapes (although there is some slight variation), and there is a reproducible standard drop size that is governed by the dropper (dispenser) tip. As simple as topical delivery may seem to achieve, there are various difficulties and shortcomings with current topical dispensing units (vials and bottles), many of which have not been previously or adequately addressed and solved.
The most common problem that the typical patient experiences when attempting to use an eye drop is the inability to introduce a drop into the eye, or simply missing the eye. There are several reasons for this. First, the normal bottle tip is not clearly visible as it approaches a normal emmetropic, hyperopic, or even myopic eye. This immediately leads to the probability that the first drop will become the “test drop”, landing on the cheek, forehead, or eyelashes, leading to waste and frustration. Second, there is a natural aversion to closely approaching objects, causing the eye to wander or drift, and look everywhere but at the dispenser tip. Again, this leads to the possibility that a drop will miss. Finally, most users are not taught how to use eye drops. They are simply given the bottle and instructed to “place one drop in the eye”.
The next important issue is one of waste. When a typical eye drop is introduced into the eye, the average inferior cul-de-sac only holds one-quarter to one-half of a standard drop. The remainder is either washed out down the cheek, or drained by the lachrymal system. Large strides in preventing waste were made when a dispenser tip was developed that delivered smaller drop sizes, thus eliminating a portion of waste. However, this advantage is negated if it takes several drops to gain access to the ocular surface. This issue is critical when evaluating cost to the patient and the healthcare system. The cost problem for the patient is obvious: the more drops they use, the greater the amount of money spent. With respect to the healthcare system as a whole, cutting costs are of paramount importance. In fact, many Health Maintenance Organizations (HMO's) will not let their members get refills on their ophthalmic medications more than once a month. The rationale behind this is simple. If the bottle has “x” number of drops in it, it should last “y” number of days. If the patient is not proficient with a high success ratio, then the drops will run out before the specified time allowed. This, in turn, leads to the patient either being without their valuable medications, or having to pay for the medications themselves.
Finally, there is the problem of contamination of the dispenser tip, and cross-contamination between patients. Since the tip is not clearly visible upon the approach to the ocular surface, it oftentimes will inadvertently come in contact with the eye or lid structures. This will lead to an inoculation of the tip with ocular flora, and be a potential source for spreading infection. Although sharing medications in general, especially eye drops, is always discouraged, many different people, whether friends or family members, often find the ease and convenience of sharing overwhelmingly tempting. Again, this can lead to cross-contamination and, in turn, the spread of infection.
Most of the current problems of efficiently dispensing ophthalmic drugs stem from user error. Therefore, it is the goal of this device to create a “user friendly” ophthalmic drug dispenser.